Solution:
First consider statement (1) alone.
m < 5 and n < 2.
Let m be 4 and n be 1.
Or mn = 4 < 10.
Next let m = -6 and n = -2.
Or mn = (-6)*(-2) = 12 > 10.
So from (1) alone we cannot definitely whether mn > 10 or not.
Next consider statement (2) alone.
1<m<3 and n^2 < 25.
Or 1<m<3 and -5<n<5.
If m = 2.5 and n = 4.4, then mn = 11 > 10.
If m = 2 and n = 4, then mn = 8 < 10.
So from (2) alone we cannot say definitely whether mn > 10 or not.
Next combine both the statements together and check.
On combining we have that 1<m<3 and -5 < n < 2.
Or -15<mn<6.
In any case mn < 10.
Or mn is not greater than 10.
The correct answer is (C).
Is mn > 10?
This topic has expert replies
Source: Beat The GMAT — Data Sufficiency |
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Rahul@gurome
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Rahul Lakhani
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Quant Expert
Gurome, Inc.
https://www.GuroMe.com
On MBA sabbatical (at ISB) for 2011-12 - will stay active as time permits
1-800-566-4043 (USA)
+91-99201 32411 (India)
